Gastrointestinal foreign bodies in pet pigs: 17 cases

Abstract Background Pigs have an indiscriminate eating behavior placing them at high risk of developing foreign body (FB) obstructions. Objectives Describe the clinical and diagnostic features, treatments, and outcome of pet pigs diagnosed with gastrointestinal (GI) FBs. Medical and surgical treatments, pig outcomes, and post‐mortem findings were also investigated. Animals Seventeen pet pigs. Methods A multicenter retrospective study was conducted. Gastrointestinal FBs were defined as swallowed objects that became lodged within the gastrointestinal tract distal to the cardia identified during exploratory laparotomy. Results Common clinical signs were anorexia/hyporexia, tachypnea, vomiting, dehydration, tachycardia, and ileus. Diagnostic imaging identified the presence of a FB in 4 cases. Upon celiotomy, the FBs were in the stomach and small intestine in 17 cases and large colon in 2 cases. Types of FB included fruit pit, diaper, and metallic objects. Of the 17 pigs, 15 (88%) were discharged from the hospital and 2 (12%) were euthanized. Conclusion and Clinical Importance Clinical signs of GI FB were similar to those reported in obstipated pigs. Diagnostic imaging has limitations for detection of FB. Surgical removal of FBs in pigs carried a good prognosis.


| INTRODUCTION
In recent decades, pet pigs have become popular in North America, resulting in a markedly increased demand of veterinary care at referral hospitals. 1,2,3,4 Pigs have a nonselective eating behavior, can swallow incompletely masticated food, and are exposed to human foodstuffs placing them at high-risk of developing gastrointestinal (GI) foreign bodies (FBs). Gastrointestinal FB obstructions are commonly encountered in small animal medicine and are life-threatening conditions; this disease appears to be uncommon or underreported in pigs. 5

| Clinicopathological findings
The CBC and BP results were available for 10 and 8 pigs, respectively.

| Diagnostic imaging
Radiographic examination of the abdomen was performed in 14 (82%) pigs. The stomach was severely distended with homogenous, soft tissue opaque material and gas in 11 (65%) pigs. Distention was subjectively graded by deviation from normal placement and comparison to radiographic findings in pigs of similar weight. Gas-distended small intestinal loops were noted in 9 (53%) pigs. A FB was identified in 4 (24%) cases. A linear metallic FB was noted in the stomach of 1 pig and 2 suspected peach pits were noted in the pylorus in another pig.
Foreign material causing pyloric obstruction was described in the other 2 pigs. A dilated fluid-filled stomach with gastric foreign material was confirmed in 1 pig, which elicited concerns of a pyloric outflow obstruction.
Ultrasonography findings were available for 6 (35%) pigs. In 3 cases, multiple hypomotile small intestine loops were noted. A mass-like object with hypoechoic and hyperechoic regions was identified in the right ventral abdomen of a pig. A FB-like material was identified in the pyloric region in another pig.

| Treatment
Fourteen pigs (82%) were treated with fluid therapy via intravenous, rectal or oral, or combination of intravenous and oral administration of fluids, or combination of rectal and oral administration of fluids. Ten pigs received intravenous constant rate infusions at rates ranging from 2 to 6 mL/kg/h (median: 2.5 mL/kg/h) consisting of isotonic crystalloid fluids (n = 4), balanced electrolyte isotonic fluids (n = 5), or 5 isotonic crystalloid fluids mixed with 5% dextrose (n = 4). Duration of IV fluid therapy ranged from 24 to 72 hours (median: 48 hours). Rectal fluid administration rates ranged from 3 to 15 mL/kg/h (median: 11 mL/kg/h). The type of rectal fluids administered includes isotonic fluids (n = 2) or balanced electrolyte isotonic fluids (n = 3). Duration of rectal fluid therapy ranged from 24 to 48 hours (median: 24 hours). Six pigs were offered free choice access to water or fruit juice or both.

| Complications
Three pigs developed complications. One pig had mild intraoperative contamination of the abdominal cavity that was treated with intravenous antimicrobial drugs and responded well to therapy (FB in cecum).
In another pig, a soft tissue abscess developed in the caudal aspect of the incision at 30 days post-surgery (FB in stomach). The abscess was debrided surgically under sedation. One pig developed constipation 2 weeks later (FB at pyloric outflow), which resolved without further treatment.

| Outcome
Fifteen (88%) pigs were discharged from the hospital while 2 (12%) were euthanized during surgery because of the poor prognosis. The median time of hospitalization for pigs that survived to discharge was 4 days (range, 2 to 8 days). The median time between admission and euthanasia in non-surviving pigs was 18 hours (range, 0.5-24 hours).
Long-term follow-up was not available for pigs discharged from the hospital.

| Post-mortem examination findings
Post-mortem examination was performed in the 2 euthanized pigs.

| DISCUSSION
In this study, the most frequently observed clinical findings were anorexia or hyporexia, tachypnea, vomiting, dehydration, hypomotility, tachycardia, ileus, and decreased demeanor. These clinical signs are similar to those reported in pigs with obstipation. 3 Therefore, clinicians should always consider FB obstruction as a differential diagnosis for pigs with decreased fecal output, anorexia or vomiting.
The FBs in our study were primarily identified within the stomach and small intestine and in most of the cases were causing a complete obstruction requiring surgical intervention. Foreign bodies located in the jejunum, spiral colon, transverse, and descending colon of pigs have been reported, but are noted as a rare occurance. 5 Studies in dogs investigating FBs located distal to the cardia showed contradictory results with some reporting that most of the obstructions occurred in the stomach 7 and others with predominant occurrence in the jejunum. 8,9 Of the FBs identified distal to the cardia in dogs, 70% caused complete obstruction. 8 It is possible that FB obstruction of the stomach and small intestine in pigs are more frequent because FBs that pass through the small diameter of the small intestine are then able to freely move distally without causing clinical signs of obstruction.
Causes of intestinal obstructions included fruit pits, diapers, and linear foreign bodies. Fruit pits and linear FBs have previously been reported to cause GI obstruction in pigs. 5 In small animals, linear FBs account for 50% to 60% of the cases in cats, and 36% in dogs. The survival rate of dogs with linear FBs varies from 78% to 98%. 7,8 Dogs with linear FBs had more severe clinical signs and an increased duration of hospitalization than their counterparts with non-linear FBs. 8,10 In our study, hospitalization period and survival rates appeared to be similar for pigs with linear and non-linear FBs. However, the small number of pigs included in this study did not allow statistical analysis to determine differences between groups.
Esophageal and gastric endoscopic FB removal is reported in humans, 11 dogs, 8,9 calves, 12 horses, 13 and donkeys. 14 Flexible endoscopy allows direct observation of the foreign material, facilitates its removal, and allows assessment of stomach integrity. Success rates for endoscopic removal of esophageal and gastric FBs in dogs ranged from 26% to 63% in early studies, however, a more recent study reported a success rate of 86% (57/66). 9 The value of endoscopic FB removal in pigs is unknown. In our study, there were no attempts to remove gastric FBs. In our study, sample 65% of the pigs had a severely distended stomach with homogenous soft tissue opaque material on radiographic examination of the abdomen, which may limit accessibility to objects located near or distal to the pylorus. Endoscopic FB removal could be beneficial in cases with a discrete FB as it is less invasive and can reduce the risk of general anesthesia or other complications associated with laparotomy (eg, peritonitis, incision infections, seromas, and abscesses). 8,5 Gastric FBs were successfully removed via gastrostomy or enterotomy with only 3 (20%) of 15 pigs developing complications (intraoperative abdominal contamination, surgical site abscess, and constipation). Generally, in small animals, gastrotomy is a routine procedure with an excellent prognosis and minimal complications, and dehiscence and peritonitis rarely occur if basic surgical rules are followed. 8,15 Our study indicates that this statement could also apply in pet pigs. In general, the enterotomy procedure itself is not associated with higher fatality rate or complications in dogs. 8 However, dogs and pigs undergoing multiple intestinal incisions have a significantly higher fatality rate than those treated with a single enterotomy. 8,5 The number of incisions was not recorded in the present study and therefore further conclusions cannot be drawn.
Gastrointestinal FBs were identified in 24% of pigs via radiographic examination. In small animals, ultrasonography detects 100% of FBs in animals, while radiographs only identify 56% of foreign bodies. 16 Ultrasonography aids in identifying intestinal perforation, serosal alterations, and mild small intestinal distension, but these abnormalities cannot be identified using radiographic examination. 16 Abdominal ultrasonography findings were reported in 6 pigs in our study, with the FB identified in 1 pig. Differences between human and pig medicine regarding the diagnostic value of abdominal ultrasonography can be explained, at least in part, by the difficulties in clearly identify abdominal structures because of their thick skin and greater abdominal fat layer. Computed tomography (CT) for evaluation of the GIT is commonly used in small animals and humans for diagnosis of GI diseases. 17 There is growing acceptance for its use in pigs for the diagnosis of GI diseases but is often declined for economic reasons. The CT examination could aid in diagnosis of GI FBs when the diagnosis is not reached by radiography or ultrasonography examination.
Surgical removal of FBs in pigs included in this study carried a good prognosis for survival. A previous report documented a successful removal of FBs in 5 of 5 pigs with intestinal obstruction. 5 The survival proportion of the pigs reported here is similar to the 88% and 92% survival proportions reported in cats and dogs, 8 respectively, undergoing celiotomy for removal of FBs located distal to the cardia. 8 Limitations of this study include those associated with the retrospective design. The small sample size of the different treatment groups also prevented the assessment of risk factors for survival and the efficacy of the different interventions. This study provides evidence that surgical removal of FBs has a good prognosis, and that FBs need to be considered as a differential diagnosis in pigs with clinical signs of vomiting, anorexia, lack of fecal passage, or lethargic behavior.

ACKNOWLEDGMENT
No funding was received for this study. Presented in part as a poster presentation at the 2020 ACVIM Forum On Demand.